Safety pilots



Oct- 2, 1962 R. s. LOVELAND ETAL 3,056,450

SAFETY PILOTS Filed Feb. 2, 1959 @l 14 IM INVENTORS ROGER S. LOVELAND NICKOLAS J. SIDARIS ATTORNEY United Sttes 3,956,450 Patented Oct. 2, 1962 free 3,056,455 SAFETY PILOTS Roger S. Loveland, Torrance, and Nicholas J. Sidaris,

Long Reach, Calif., assignors to Minneapolisulloneywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Filed Feb. 2, 1959, Ser. No. 799,438 7 Claims. (Si. 158-123) This invention relates to safety pilots and, more particularly, to a thermoelectric generator of the type which requires no primary air for the burner of the generator.

Generators or safety pilots of this type are well known in the art but this invention is directed to an improved arrangement of the flame sensing unit land the burner for heating it as well as improvements in the details of the burner per se.

One of the objects of the invention is to provide a safety pilot which provides an annular llame for igniting a main burner as well as an annular llame for heating a temperature responsive unit, such as a thermocouple or thermopile.

Another object of the invention is to provide an inexpensive non-primary aerated burner which provides an annular flame primarily for igniting a main burner or a plurality of main burners, with an additional llame primarily for heating a llame sensing unit and so designed that the llame for heating the llame sensing unit extinguishes `before the flame reduces to a size insulllcient for igniting the main burner.

A still further object of the invention is to provide a safety pilot having an annular burner wherein means is provided to divide the llame into one primarily for heating the flame sensing unit and another primarily for igniting a main burner and which is not readily extinguished by a downdraft over the unit.

Still further objects of the invention will become apparent upon reading the following detailed description of the invention in conjunction with the drawing wherein:

FIGURE l is a vertical elevational View of the burner with portions thereof shown in cross section;

FIGURE 2 is an end elevational View of the safety pilot;

FIGURE 3 is a plan view of the invention; and

FIGURE 4 is a View of the invention taken along the line 4-4 of FIGURE 2.

Referring now to FIGURE l of the drawing, the safety pilot consists of a mounting bracket 11 having holes 12 therein for mounting the safety pilot adjacent a main burner (not shown) by means of bolts (not shown). Extending through a hole 13 in a laterally extending arm 11a of the bracket 11, is a mounting tube 14 for supporting a thermocouple 15 in a conventional manner. These conventional thermocouples are approximately three inches long. The tube 14 is secured in the bracket arm 11a by brazing, as shown at 16 in the drawing. A pair of concentric leads 17 and 19, with insulation 18 therebetween, are secured to the thermocouple 15 and the thermocouple is held in the sleeve 14 by means of a clamping nut 20.

, Welded to the top of the arm 11a, as at 21, is an arcuate support 22 that is notched out at 23 to provide two spaced legs 22a and 22b.

Welded to the upper portion of the support 22, as at 24, is a sleeve 25 having an inwardly extending flange 26. Extending through aligned holes 27 and 23 in the sleeve 25 and support 22, respectively, is the end of a tube 29 for conducting gas to the interior of the tube 25. The tube is secured to the support 22 by means of the soldered or brazed connection 3l?.

Extending through the tube 25 and in gas tight sealing relationship with the inner periphery of the flange 26, is a tube 31 that has an enlarged diameter portion 32 at its upper end, forming a shoulder 33, lying in a plane substantially midway between the hole 27 in the sleeve 25 and the upper end of the sleeve 25. The lower end of the sleeve 31 is turned in slightly to help retain the annular shape thereof.

The upper end of the tube 32 extends above the upper end of the sleeve or tube 25 and has an upwardly bowed and outwardly extending flange 34 thereon that projects slightly beyond the outer periphery of the tube 25. Slightly below the llange 34, are three arcuate slots 35 in tube 32, separated yby lands 36, which serve as supports for the flange 34.

A gas spreader 37, shown in more detail in FIGURE 4 of the drawing, has a plurality of concentrically arranged notches 38 therein and has a sleevelike portion 39 -that lits snugly around the tube 31 and abuts against the shoulder 33 where it joins the enlarged diameter portion 32. The periphery of the spreader is of the same diameter as the tube 25 so that when it is positioned in the tube 25, the notches 33 provide a plurality of passages between the spreader and the tube 25 so as to distribute the gas entering the tube 25 to all portions of the space between the upper end of the tube 25 and the enlarged diameter portion 32. This assures a uniform flame all the way around the burner tip where it issues laterally outwardly between the flange 34 and the upper end of the tube 25 and inwardly through the slots 35 to the interior of the tube 31 and against the llame sensing unit 15.

For conducting low pressure gas to the tube 25, the other end of the tube 29 extends into a conduit connector 4t) welded to the bracket arm 11a, as at 41. The end of the tube 29 that extends into the connector 40, is outwardly flared at 29a to rest against a frusto-conical surface 42 at the inner end of a bore 43. The lower end of the connector 40 is externally threaded at 44 to receive a clamping nut 45 thereon. A burner spud 46 has an orifice plate 47 embedded in its upper end and is beveled at its upper periphery to sealingly clamp the llange 29a against the frusto-conical surface of the connector 4t). The lower end of the burner spud 46 has an axial bore therein which is outwardly flared at its lower end to receive a wedge shaped sleeve 48. A conduit 49 extends through an opening in the nut 45 and through the sleeve 48 into the spud 46 and is sealingly clamped therein by the nut 45 being threaded onto the connector 40 so as to force the spud 46 against the llange 29a and wedge the sleeve 43 between the conduit 49 and the lower end of the spud.

Operation Assuming that the safety pilot unit described above is installed in a heating system with the bracket 11 bolted to the side of a main burner, the conduit 49 connected to a gas supply line and the concentric leads 17 and 19 connected to a manually reset, thermocouple energized, magnetic valve in the gas supply line, the heating `system may be placed in operation by opening the safety valve manually to permit gas to llow through the conduit 49 and to the burner tube 25 so that the gas issuing from the slots 35 and outer annular slot may be ignited. The gas is metered by the orice in the plate 47 and is spread evenly around the tube '32 by means of the spreader 37. The gas that issues through the slots 35 provides substantially an annular llame, due to the narrowness of the lands 36 between the slots 35, with the llames extending inwardly and upwardly over the upper end of the thermocouple 15. The slot between the upper end of the tube 25 and the outer end of the flange 34 provides a llame for igniting a main burner. If the pressure reduces, the inner flame or the outer fiame or both will fiutter to cause complete extinction of the pilot before the flames are so small as not to be able to ignite the main burner.

Due to the fact that the fiange 34 is upwardly bowed or dished, the pilot flame is protected from being blown out due to the fact that a portion of the flame is held up under the fiange 34. Therefore, a downdraft, that would otherwise extinguish the fiame at the slot 35 as well as the outer fiame, will only succeed in extinguishing the major portion of the flame, leaving the protected portion of the flame to reignite the gas issuing from the orifices 35 and the outer annular slot when the downdraft has ceased. This fiame retention is also aided by the fact that the outside diameter of the flange 34 is slightly greater than the outside diameter f the tube 25, providing a slight overhang.

While most of the heating of the thermocouple 15 is done by the inner fiame, the thermocouple is additionally heated by the annular outer flame that rises upwardly as Well as outwardly from under the fiange 34 due to the low gas pressure which is only slightly above atmospheric pressure. At higher gas pressures, the outer fiame is thrown further away from the thermocouple as it rises so that a substantially uniform heating of the thermocouple occurs at all operating gas pressures.

While the invention has been illustrated with the thermocouple 15 as the ame sensing unit, it is to be understood that a liquid or gas filled capsule connected by a tube to a bellows operated valve or switch could also be used in place of the thermocouple. It is to be understood that the scope of the invention is to be determined from the appended claims.

We claim as our invention:

l. A thermoelectric generator comprising a first burner tube, a second smaller burner tube positioned substantially concentrically within and in spaced relationship with said first tube, means closing the space between said tubes near the lower ends thereof, said second tube having a projection beyond the end of said first tube and terminating in an outwardly extending fiange that projects over said first tube so as to form a slot therebetween, said second tube also having an opening in the wall thereof near said flange, one of said tubes having an aperture therein for the admission of fuel only, and means between said aperture and said opening for distributing the fuel substantially evenly between said tubes so as to provide a uniform flame at said slot and opening, and a thermocouple unit supported substantially concentrically within and spaced from and projecting above said tubes.

2. A safety pilot comprising a first burner tube, a second smaller burner tube positioned substantially concentrically within and in spaced relationship with said first tube, means closing the space between said tubes near the lower ends thereof, said second tube having a projection beyond the end of said first tube and terminating in an outwardly extending ange that projects over said first tube so as to form an opening therebetween, said second tube also having an opening in the wall thereof near said fiange, one of said tubes having an aperture therein for the admission of fuel only, and a flame sensing unit supported substantially concentrically within and spaced from and projecting above said tubes.

3. A safety pilot comprising a first burner tube, a second smaller burner tube positioned substantially concentrically within and in spaced relationship with said first tube, means closing the space between said tubes near the lower ends thereof, said second tube having a projection beyond the end of said first tube, an outwardly extending and upwardly bowed ange on the upper end of said second tube that projects o-ver `said first tube so as to form a slot therebetween, said second tube also having an opening in the wall thereof near said fiange, one of said tubes having an aperture therein for the admission of low pressure fuel, and means between said aperture and said opening for distributing the fuel substantially evenly between said tubes so as to provide a uniform flame at said slot and at said opening, and a flame sensing unit supported substantially concentrically within and spaced `from and projecting above said tubes.

4. A thermoelectric generator comprising a first burner tube, a second smaller burner tube positioned substantially concentrically within and in spaced relationship with said first tube, means closing the space between said tubes near the lower ends thereof, said second tube having a projection beyond the end of said first tube and having at its upper end an outwardly extending and upwardly bowed fiange that projects over said first tube so as to form a slot therebetween, said second tube also having an arcuate slot in the wall thereof near said flange, one of said tubes having an aperture therein for the admission of low pressure fuel only, and means between said aperture and said slots for distributing the fuel substantially evenly between said tubes 4so as to provide la uniform flame at each of said slots, and a thermocouple unit supported substantially concentrically within and spaced from and projecting above said tubes, said thermocouple unit being substantially heated by both of said ames at normal gas pressure but heated substantially only by the ame from the first tube at high gas pressures.

5. A safety pilot comprising Ka first tube having an inwardly extending fiange around its lower end, a second tube extending through said first tube and being in gas tight engagement with the periphery of said fiange, said second tube having an extension beyond the upper end of said first tube, an upwardly bowed `and transversely extending ange on said extension projecting beyond the upper end of said first tube and forming a slot therebetween, said extension having an aperture therein in a pl-ane horizontally between the top of said first tube and said upwardly bowed fiange, one of said tubes having a low pressure gas supply passage extending therethrough in the lower portion thereof, a gas spreader intermediate the ends of said first tube, and a temperature responsive means supported within said second tube in spaced relationship with the inner wall thereof opposite said aperture.

6. A safety pilot comprising a first tube, a second tube extending through said first tube, means closing the space between said tubes at the lower portions thereof, said second tube having an extension beyond the upper end of said first tube, a transversely extending fiange -on said extension projecting over the upper end of said first tube and forming an opening therebetween, said extension having an aperture therein in a plane horizontally between the top of said first tube Vand said fiange, one of said tubes having a low pressure gas supply passage extending thererthrough in the lower portion thereof, and a temperature responsive means supported within said second tube in spaced relationship therewith opposite said aperture land extending above said flange a sufficient amount so that it may be substantially heated by a fame issuing from said opening at normal gas pressure.

7. A safety pilot comprising a first tube having an inwardly extending flange around its lower end, a second tube extending through said first tube and being in gas tight engagement with the periphery of said flange, said second tube having an extension beyond the upper end of said first tube, an upwardly bowed and transversely extending flange on said extension projecting beyond the upper end of said first tube and forming a slot therebetween, said extension having an aperture therein in a plane horizontally between the top of said first tube and said upwardly bowed fiange, one of said tubes having a low pressure gas supply passage extending therethrough in the lower portion thereof, a gas spreader intermediate the ends of said first tube, said spreader having a washer- `shaped portion extending between said tubes and having a plurality of evenly spaced notches in its outer periphery, and a temperature responsive means supported within said second tube in spaced relationship therewith opposite Vsaid 5 6 aperture and extending above said ange so that it may 2,311,778 Reinhart Feb. 23, 1943 be heated substantially by a ame from said slot at 2,340,899 Ray Feb.8, 1944 normal gas pressure. 2,474,547 Patch June 28, 1949 2,526,112 Biggle Oct. 17, 1950 References Cited in the le of this patent 5 2,649,490 Greenamyer Aug. 18, 1953 UNITED STATES PATENTS Eile ---B -E ebig; rum aug ec. 2,026,054 Morgan Dec- 31 1935 2,833,843 Jackson et al May 6, 1958 2,107,575 Matthews et al. Feb. 8, 1938 

